Aspect of the East in fact (5)
I believe the answer is:
facet
'aspect' is the definition.
(I know that aspect can be written as facet)
'east in fact' is the wordplay.
'east' becomes 'e' (abbreviation).
'in' indicates putting letters inside.
'e' going into 'fact' is 'FACET'.
'of the' acts as a link.
(Other definitions for facet that I've seen before include "Aspect or feature of something" , "Angle" , "Flat surface on a cut gem" , "Look" , "view" .)